Generally, the existing CD+G is an audio CD format, which has limited capabilities to store additional graphics data and is mostly used in karaoke applications. The audio part of CD+G is playable on any standard Audio CD. For displaying graphics, a CDG player, a special CD player with TV output, is required, e.g. a karaoke CD player. In the CD+G format, audio data is recorded in a program area, while additional data can be stored in a program management area, which is divided into eight sub-code channels, channels P to W. The P-channel indicates the start and end of each track by toggling between 0 and 1. The Q-channel contains time-codes and a table of contents Further additional data contained in the sub-code channels R to W, may allow graphics and text to be displayed while music is being played, as used e.g. for representing still pictures or for representing letters e.g. for karaoke.
The CD+G standard defines different modes of CD+G, which are the ZERO, GRAPHICS (karaoke), MIDI and USER mode:                ZERO mode is a mode in which no operation is done on a display screen.        GRAPHICS mode allows to represent pictures or symbols, e.g. for karaoke.        MIDI mode provides a 3.125 kb/s maximum data channel for the Musical Instrument Digital Interface (MIDI) data as specified by the International MIDI Association.        USER mode is intended for professional applications. The meaning of the data is application specific.        